Improvement of arterial blood flow, in patients with obstruction of the arteries to the leg, is usually obtained by surgically bypassing the occluded arteries, or by removing obstructions with devices that are inserted into the blood vessel. In elderly patients who have undergone multiple vascular procedures, the deterioration of arterial blood flow can lead to severe pain (ischemic neuritis), tissue loss (arterial ulcers) or toe loss (gangrene). When the arteries cannot be repaired anymore, this situation may lead to leg amputation.
Blood flow in patient's extremities, particularly the legs, markedly decreases during extended terms of confinement. Such pooling or stasis is particularly acute in surgery and during recovery periods immediately thereafter.
In the past, numerous devices and methods have been disclosed for aiding cardiocepital venous flow to prevent venous hypertension. These devices and methods usually included the use of boots placed around the foot and leg and pressure was applied to the foot and leg. However, the prior devices were extremely cumbersome and usually required the patient to remain immobile. In addition, the prior devices did not concentrate the pressure in those areas in which it was most effective, namely, the soft tissue areas of the foot and leg, and therefore they did not operate efficiently. Also, the prior devices and method could not be used for an ambulatory patient because of the need to be connected with stationary equipment, which in turn needs to be connected to a mains power supply.
Certain treatments comprise of a massager composed of a linear compressor having a piston reciprocated by force of electromagnetic attraction to produce compressed air at a safe pressure with a relatively small difference between the rated pressure and the maximum pressure, a distributor for allowing the compressed air fed from the compressor to be selectively discharged therefrom and a bag having a plurality of air tight sections which are successively expanded by receiving the compressed air fed from the distributor. For example, U.S. Pat. No. 4,577,626 relates to a massager which utilizes compressed air at a safe pressure and has a simple structure and easy operation.
Other devices have comprised pressure-fluid massage machines and devices which have been provided with a bag means of rubber or the like, which is wound around a portion to be treated on the subject and expanded by supplying thereto a pressure fluid such as compressed air to exert massaging pressure upon the portion to be treated, thereby massaging the subject. In the massager of this type, to improve the massaging effect, the bag means is partitioned off into air-tight sections so that a pressure fluid can successively be fed into the air-tight sections by use of a distributing valve to give the massaging pressure to successive parts of the portion to be treated on the subject in consequence of the expansion of the bag means.
U.S. Pat. No. 5,218,954 teaches of a device which operates by providing simultaneous and rapid compression of the soft tissues of the calf, ankle and foot, thereby completely and instantly emptying the veins, and reducing venous pressure to zero in a sitting patient position. Upon rapid deflation of the boot, the reduced venous pressure results in an increased driving pressure for the arterial blood flow. The increased arterial blood flow will occur approximately one second after deflation, and will last for approximately 4-14 seconds. The compression phase itself does not improve arterial flow, but impedes arterial flow; therefore compression is kept as short as possible. The design of the compression boot is fashioned for this purpose. A stiff, non-elastic outer case for the lower leg and foot reduces the amount of fluid (air) needed to inflate the relatively small bladder.
One use for the above mentioned devices is the prevention of deep venous thrombosis (DVT) which sometimes occurs in surgical patients when they are confined to bed. When a DVT occurs, the valves that are located within the veins of the leg can be damaged which in turn can cause stasis and high pressure in the veins of the lower leg.
Patients who have this condition often have leg swelling (oedema) and tissue breakdown (venous stasis ulcer) in the lower leg.
Certain manufacturers provide cuff-like arrangements and similar types of devices;—whilst being designed for and providing assistance to patients with DVT, have been found to provide benefit in diabetic patients. However, a problem exists in that the equipment is electrically powered, and a patient is required to remain immobile for at least 6 hours per day during therapy.
U.S. Pat. No. 4,502,470 provides a physiologic device having a fluid filled compartment. This is surrounded by an outer sheath fastened to the foot. The sheath holds the compartment under the instep and directs the hydraulic forces into the ankle and lower leg. Pressure produced by walking on the fluid compartment is used to compress the lower leg. This prevents swelling and it can heal ulcers due to bad veins. U.S. Pat. No. 5,218,954 teaches of a device and method for the purpose of increasing arterial blood flow to the lower leg, calf, ankle and foot. The device is a compression boot, or cast, and consists of a mono-compartment bladder enclosed in a non-elastic outer envelope connected to an air compressor with regulator valve, providing fast inflation to pressures over 80 mm Hg. Decompression occurs rapidly, by venting a large valve to the atmosphere. During the resulting low pressure phase, there is a marked increase in arterial blood flow.
U.S. Pat. No. 4,624,244 and U.S. Pat. No. 4,941,458 teach of a device—and corresponding method of use—for an ambulatory patient, wherein the device comprises a cuff for placement around the lower calf and foot of a person suffering from circulatory problems. In this device, air bladders are pulsated about the lower calf and soft tissue of the foot by means of a pump and pulse-inducing flow control means. The cuff does not provide a boot as such and various fasteners are secured so that the cuffs fit snugly, but not so tight as to impair circulation of a foot. When the bladders are inflated, they will bulge inwardly toward the adjacent soft tissue to provide good pressure against the deep veins. US2003/0013997 provides a venous pump to promote circulation; a bladder placed under the sole of a wearer of such a boot inflates a cuff placed around a calf of the wearer of the boot whereby walking provides cyclical compression of the bladder, which in turn inflates the cuff. U.S. Pat. No. 6,589,194 teaches of a self-powered inflatable compression device for use in promoting circulation. However, this device—which comprises sequentially filled pressure sleeves situated about a leg is wrapped in bandage; it provides no support for ulcerated feet and provides a device that is suitable for indoor use.
Despite the known advantages of compressive forces applied to the legs and feet, there remains a need for simple, truly mobile device without the need for further boot arrangements, which enable ambulatory movement and conveniently do not depend on electrical power being available, either from batteries or mains supply. Additionally there is no system available operable to provide a boot or other form of footwear which enables the user to be supported whereby compressive forces encountered in walking do not compromise healing of an ulcerated wound or similar lesion.
The present invention seeks to address some of the problems encountered by prior art limb compression devices and methods. In particular the present invention seeks to provide a boot which can stimulate blood flow. A further object to the invention is to provide a boot with a sole which is adaptable to conform with various shapes and conditions of human feet. The present invention seeks to provide a new type of footwear that has a therapeutic benefit for diabetic patients with circulatory problems in their foot and also enables the technique of “off loading” the foot to assist in the healing of any wounds present.
The present invention further seeks to provide a boot that can improve arterial blood flow in a leg in order to treat ischemic pain and ulceration, and obviate the need for amputation, thereby eliminating the risks of surgery.